Is it true that you burn fewer calories as you age? And what does this mean for our diet?
Look at calories and burning them as the first step to being alive, says Herman Pontzer, a professor of evolutionary anthropology at Duke University. Food gives your body the fuel it needs to stay healthy.
Your age—among many other factors—can greatly affect how many calories you need to maintain your weight and basic body functions.
Here’s what you need to know.
How your age affects the calories you burn
Dr. Pontzer says body size is the single most important factor affecting your caloric needs. The bigger your body, the more calories you need.
But he points out that the stage of life you are in is also crucial.
Babies and children, for example, need fewer calories than adults because they are smaller. But when you calculate how many calories they consume relative to their body size, it’s actually more than adults consume as they grow and develop.
More physical activity also increases the number of calories you burn, says Anna Maria Siega-Reese, dean of the School of Public Health and Health Sciences and professor of nutrition at the University of Massachusetts Amherst. He was the lead author of the 2023 report by the National Academies of Sciences, Engineering and Medicine, which estimates the calorie needs of people in the United States and Canada.
Example 1
According to that report, a 40-year-old sedentary man weighing about 90 kilograms needs about 2,700 calories per day to maintain weight and basic body functions. But if an athlete trains for several hours every day, he would need about 3,500 calories a day.
According to the same report, starting around age 19, caloric needs decline slightly each year — about 11 calories for men and seven calories for women, says Susan Roberts, senior associate dean for basic research at Dartmouth’s Geisel School of Medicine.
Example 2
For example, a 77 kg woman who walks 60-80 minutes every day will need 2450 calories per day at age 20, but by age 60 these calories will drop to 2150 and by age 80 to 2000.
This age-related decline in calories is usually more noticeable after the 60s and may manifest as weight gain or decreased appetite. As people age, they lose muscle mass and accumulate fat, which burns fewer calories. The brain, which is the most metabolically active tissue in the body, is shrinking in size and requires less energy.
It’s common for people to decrease their physical activity as they age, further reducing the number of calories they burn each day.
This means you burn fewer calories for your eating habits
Dr. The good news, Pontzer says, is that your appetite will likely decrease with age in line with your needs.
But as you age, it’s important to make sure you’re getting the right balance of nutrients.
For example, studies show that starting at age 50, your body needs more of certain nutrients, such as calcium, vitamin B6, vitamin D, and protein, even though you consume fewer calories throughout the day.
Therefore, you should focus on foods that provide you with more nutrients, such as fruits, vegetables, whole grains, and lean protein.
Dr. Roberts agrees. When you’re in your 20s and 30s, he says, “you have room for chocolate or beer or a piece of cake.” But if you’re 80 years old and eating only 1,500 calories a day, there’s even less room for treats.
He believes it is wise for older adults to take a multivitamin supplement to cover any nutritional deficiencies. But even so, a good diet is still important to ensure you get other important nutrients like protein, fiber and healthy plant compounds.